OK i checked up my truck all fluids etc, the rear 9.75, i removed the nut and it didnt fluid out which it suppose be, right ? I used my finger into the hole i could feel its little low.

So i went to Pep boy for purple gear fluid and was planning to fill it fluid but the fluid came out ??

Am i right, its cuz of hot it expand fluid ?? am i suppose to fill the fluid when its COLD ?

Thanks!
YOMAN!

 

I think it's just suppose to be up to the fill hole with the truck on level ground. I would expect cold would be the time to check it but expansion can't be much to make any difference.

 

gear oil is thick enough to stick to the gears. If the diff has been turning, oil will still be on the gears when you check the level. That oil will settle if you let it sit a while. At that point, the level should be up to the fill hole or even slightly (1/2") below is ok.